I have been watching this thread with interest but have not chimed in as I did not have any clear advice.
So tripping AFCI on an unrelated circuit is really weird. I am thinking there are a few ways that the Tesla could influence this:
1. As the Tesla ramps up charging it may be pulling the voltage down on your service over all. There may be some condition on that AFCI branch circuit that was very close to tripping the circuit but it did not quite do it. Once the voltage is dragged down enough it may put it over that threshold. (AFCI trip mechanisms are complicated and driven by a microprocessor)
2. The Tesla may be creating some kind of noise or harmonic on the electrical service that again is pushing the AFCI over some limit. This would be really hard to troubleshoot without advanced tools and skills. We have seen Tesla’s trip some GFCI breakers, perhaps for similar reasons.
3. AFCI’s also I believe have some basic ground fault circuitry in them. This is more of a long shot, but if there was some really weird leakage of current from the Tesla circuit into the AFCI circuit (to like nicked wires that are touching in the same conduit) it could cause an issue like this. But that is such a long shot I don’t even think I should have mentioned it.
My first course of action here would be to look at the voltage when you first plug the car in (immediately before charging starts) and then compare that to the voltage after the car fully ramps up and has been charging for a minute or so. If that drop is excessively high that could indicate other issues.
Next, I would troubleshoot the circuit in question. There are two paths you could start with:
1. Replace the breaker with a new one. The newer models may be a little less sensitive than the old ones (I would check if your current breaker is still sold or if it has been superseded by a new one). This by itself could solve it if your breaker is bad or just the old model is overly sensitive.
2. The other thing to do is to try to track down a device on the circuit that may be causing it. Catalog every receptacle/light/device on the circuit and disconnect/turn things off and see if the issue occurs. It could be a bad device that has a legit frayed cord and is causing arcing, or it could just be a device that always causes nuisance trips (that is not otherwise malfunctioning). If is not obviously isolated to one device, then you may need to tear into every single receptacle/switch box/junction box and make sure all the wires are right and not touching each other. I recently upgraded my in-laws to some a AFCI breakers and they were having nuisance trips when running relatively high current loads on the circuit (but not isolated to a single device). I found a receptacle where the bare ground wire was touching the neutral screw. So this had probably been that way for decades. Some current was returning to the transformer via the ground path rather than via the neutral. This was causing trips on the AFCI breaker since it also has some
GFCI like functionality.
I know this sucks, but these issues can be very difficult to troubleshoot. I do find is extremely odd that the Tesla causes nuisance trips on unrelated 120v circuits! Not good!
Please do report back on any resolution or new learnings!
